Some Ecological Consequences Of The Physiological And Biochemical Effects Of Petroleum Compounds On Marine Mollusks

The problems of relating the results of experiments in the laboratory to events in nature are twofold: to equate the response to a single variable (hydrocarbons) with the natural variability in the biological material in a multivariate environment, and to consider whether the response established experimentally has any relevance to the animal's chances of survival and reproduction (i.e. its fitness) in the natural population. Recent studies of the effects of petroleum hydrocarbons on marine invertebrates are reviewed, with an emphasis on the physiological and cytochemical responses by bivalve molluscs. The dose-response relations that emerge suggest the intensity of the 'signal' that must be detected in nature if the chronic, sublethal effects of petroleum pollution are to be measured. The natural variability in these physiological and cytochemical processes are then reviewed and the main causes of variability in natural populations, both endogenous and exogenous, discussed. These results indicate the extent of the `noise' above which the signal from possible pollution effects must be detected. The results from recent field studies on the common mussel, Mytilus edulis, are discussed. The results are as complex as expected, but it proves possible to reduce the variance in the measured responses so that pollution effects, including those due to hydrocarbons, can be detected. The ecological consequences of the observed effects of petroleum hydrocarbons are then discussed in terms of reproductive effort and reproductive value. Considerable variation between populations exists here also and this can be used to help in the interpretation of the extent of the impact of the environment on the ecology of the population. The result is to place the findings of the laboratory experiments in an ecological context of natural variability and of the physiological costs of adaptation.

Some Practical Considerations In The Measurement Of Pollution Effects On Bivalve Mollusks And Some Possible Ecological Consequences

A consideration of some physiological (rates of oxygen consumption, the scope for growth) and cellular (the cytochemical latency of a lysosomal enzyme) processes in bivalve molluscs suggests that animal size and seasonal changes related to the gametogenic cycle are important sources of natural variability. Correcting for size using regression techniques, and limiting measurements to one part of the gametogenic cycle, reduces observed natural variability considerably. Differences between populations are then still apparent, but the results of laboratory experiments with hydrocarbons from crude oil suggest that it should be possible to detect sub-lethal effects due to pollution (the ‘signal’) in the presence of the remaining natural variability (the ‘noise’). Statistical considerations, taken together with results from current studies on Mytilus edulis and Scobicularia plana, indicate that sample sizes of 10–15 individuals should suffice for the detection of possible pollution effects. The physiological effects to be expected in the presence of sub-lethal levels of polluting hydrocarbons are on a scaie that can cause significant ecological damage to a population through a reduction in fecundity and the residual reproductive value of the individuals.

Ecological And Metabolic Studies On Free-Living Nematodes From An Estuarine Mud-Flat

Nematodes from a mud-flat in the river Lynher estuary, Cornwall, U.K., have a population density ranging between 8 and 9 × 106 m−2 in the winter months, corresponding to a dry weight of 1·4 and 1·6 g m−2. They reach a peak abundance of 22·86 × 106 m−2 (3·4 g) in May. About 40 species are present, and the species composition remained seasonally stable over the period of study. Analysis of age-structure suggests that the major species have continuous asynchronous reproduction. Respiration rates of 16 species have been determined at 20 °C using Cartesian diver respirometry. For five species, respiration/body size regressions were obtained in the form log10R = log10a+b log10V, where R = respiration in nl O2 ind−1 h−1 and V = body volume in nl: Mesotheristus setosus (log10a = −0·04,b = 0·74), Sphaerolaimus hirsutus (log10a = 0·11, b = 0·68), Axonolaimus paraspinosus (log10a = 0·00, b = 0·79), Metachromadora vivipara (log10a = −0·59, b = 1·07), Praeacanthonchus punctatus (log10a = 0·00, b = 0·55). For the remaining 11 species, several animals were used in each diver and, by assuming b = 0·75, log10a′ values were calculated: Viscosia viscosa (log10a′ = 0·188), Innocuonema tentabundum (−0·012), Ptycholaimellus ponticus (−0·081), Odontophora setosa (−0·092), Sphaerolaimus balticus (−0·112), Dichromadora cephalata (−0·133), Atrochromadora microlaima (−0·142), Cylindrotheristus normandicus (−0·150), Terschellingialongicaudata (−0·170), Sabatieria pulchra (−0·197), Terschellingia communis (−0·277). These values are compared with recalculated values for other species from the literature. Annual respiration of the nematode community is 28·01 O2 m−2, equivalent to 11·2 g carbon metabolised. Community respiration is compared with figures from N. American saltmarshes. At 20 °C, a respiration of about 61 O2 m−2 year−1 g−1 wet weight of nematodes appears to be typical. Annual production is estimated to be 6·6 g C m−2. The correlation between feeding-group, body-size, habitat and the repiration rate of individual species is discussed.

The importance of high frequency data in ecological modelling.

The purpose of this note is to discuss the role of high frequency data in ecological modelling and to identify some of the data requirements for the further development of ecological models for operational oceanography. There is a pressing requirement for the establishment of data acquisition systems for key ecological variables with a high spatial and temporal coverage. Such a system will facilitate the development of operational models. It is envisaged that both in-situ and remotely sensed measurements will need to combined to achieve this aim.

Ecological Investigations with the Continuous Plankton Recorder: The Phytoplankton in the Southern North Sea. 1932-37.

1. The changes in the composition and distribution of the plankton of the southern North Sea have been investigated month by month, from June 1932 to December 1937; the present report deals with the phytoplankton. The survey was carried out by the Continuous Plankton Recorder, towed at a standard depth of 10 metres, by ships on regular steamship lines across the North Sea from Hull towards the Skagerrak, to Bremen and to Rotterdam, and later between London and Esbjerg. 2. The material and methods are described, together with a discussion on the validity of this type of survey and some comparison of its results with those obtained by other methods (pp. 76-86). 3. Particular attention has been paid to Rhizosolenia styliformis (pp. 92- 107), Biddulphia sinensis (pp. 108-115), Phaeocystis (pp. 149-153), and the Dinoflagellates (pp. 134-149); of these the first three are known to be of particular importance in relation to the herring fisheries. More generalised data are available for the principal diatoms other than R. styliformis and B. sinensis (pp. 116-134). 4. The main part of the work is an ecological study of the phytoplankton changes in time and space over the 5½ years. Each year is marked by some distinct variations in the abundance and the times of increase, maximum numbers and decline as recorded in the different forms. These variations in the annual cycles are compared on the different lines by a series of graphs arranged against a time scale of months, a set for each year being placed side by side (Plates I-XXI). More detailed studies by more frequent records were made in the autumns of 1934, 1935, 1936 and 1937 (cf. Figs. 3 and 4). The changes in spatial distribution are shown by a series of monthly maps arranged in a similar manner for each year (Plates XXII-LXIV). These intensive studies of the changes in time and space are also intended to form the basis for correlations with other features in the general ecology of the area (e. g. the zooplankton, hydrology, meteorology and fisheries) to be made in later publications. 5. Whilst each form has shown its own peculiar features, a trend towards a general increase in the phytoplankton as a whole has been observed during the period, although the years 1934 and 1936 have in some respects shown deviations and regressive features, and not all organisms have revealed the same trend. The possible relation of this gradual trend to other events observed in recent years in these and neighbouring waters is discussed (pp. 162-167). 6. The application of these results to the study of patchiness (pp. 154-158), inter-relationships in the plankton (pp. 159-160) and to water movements (pp. 160-162) is briefly discussed.

Ecological Investigations with the Continuous Plankton Recorder: The Copepoda of the Southern North Sea. 1932-37.

I. The monthly changes in the distribution and abundance of the Copepoda in the southern North Sea have been investigated from June 1932 to December 1937 by using the Continuous Plankton Recorder. This was towed at a standard depth of 10 metres by ships sailing on regular lines from Hull to Rotterdam, to Bremen and towards the Skagerrak, and later from London to Esbjerg. 2. The methods are described and those limitations which apply more particularly to the Copepoda are discussed (pp. 175 to 186 and 198 to 203). 3. The first part of the report deals with the Copepoda as a whole, i.e. the total population. The difference between the summer and winter distributions is stressed. The variations in numbers from year to year are found to be considerable and it is suggested that they are sufficiently large to be reflected in the success or failure of the broods of those fish which are at some period of their development dependent upon the Copepoda for food. 4. The second part deals with the data concerning the constituent species or groups of allied species ; a list of these is given on p. 197. 5. The group Paracalanus + Pseudocalanus was by far the most abundant and together with the genera Temora and Acartia was found to be responsible for most of the fluctuations in the population (pp. 205 to 208). 6. The distributions, seasonal and spatial, of the other common forms are described, with the exception of that of Oalantts finmarchicus which is to be the subject of a later report. 7. The recorder results are compared with the findings of the International Council survey from 1902 to 1908; some marked disagreements are discussed (pp. 227 to 232). 8. The appearance of the northern forms Oandacia armata and Metridia lucens during the winters of 1932-33, 1933-34 and 1937 are recorded (pp. 222 to 223) 9. A summarised account of the main seasonal changes in the area is given (pp. 232 to 234) and followed by a brief comparison of the 5½ years investigated.

Ecological Relations Between the Herring and the Plankton off The North-East Coast of England

I. 430 plankton samples, which were taken by several herring drifters using the Continuous Plankton Recorder in the Shields fishing area during the summer seasons of 1931 to 1933, are analysed to show the main changes in the plankton during those seasons. 2. A comparison is made between the proportions of the different zooplankton organisms found in the plankton and the proportions of these recorded by Savage (1937) in the stomachs of herring obtained from drifters working in the same area and during the same time. The comparisons are made for 29 ten-day periods in the seasons 1931 to 1933, and in addition, for 6 ten-day periods relating to a single drifter which obtained both plankton and stomach samples at the same time in 1932. 3. The comparisons in 2 provide evidence that the herring feeds by selecting certain organisms by individual acts of capture and not by swimming open-mouthed to strain out the plankton indiscriminately: (a) Calanus and Temora in the stomachs either correspond fairly closely to the proportions in the plankton or they may be in very much higher proportions. The latter is always true regarding Anomalocera. (b) Acartia, Oithona, Cladocera and Lamellibranch larvae are always in larger proportions in the plankton than in the stomachs; this applies also to Centropages with two insignificant exceptions. (c) There is a close correspondence between the numbers of Limacina and Sagitta in the plankton and stomachs in the latter half of the 1931 season, but not during 1932 and 1933, when the numbers in the stomachs were insignificant ; during the former period there was a great scarcity of Calanus in the plankton.

Ecological Investigations with the Continuous Plankton Recorder: The Zooplankton (other than Copepoda and Young Fish) in the Southern North Sea, 1932-37.

I. The report describes the main monthly changes in the distribution and abundance of the zooplankton, other than Copepoda and young fish (dealt with in separate reports), over the southern part of the North Sea from 1932 to 1937. The work is part of the survey carried out by Continuous Plankton Recorders towed at a depth of 10 metres on regular steamship lines between England and the Continent. 2. The limitations to the sampling method are discussed, and it is shown to be unsuitable for recording Mysidacea and Euphausiacea on account of their marked diurnal variation due presumably to vertical migration; they are omitted from the report. 3. The changing distribution of Sagitta, Limacina, Clione, Lamellibranch larvae, Cladocera, Caprellid Amphipoda, Decapod larvae, Echinoderm larvae and Oikopleura are shown in a series of monthly charts while their seasonal fluctuations are compared in time-chart histograms. 4. The Alima larvae of Squilla are recorded on a few occasions in the regions where the Channel opens into the North Sea. 5. The distributional characteristics of the different forms, i.e. their tendencies to even or " patchy " production, are compared.

Biological and ecological traits of marine species

This paper reviews the utility and availability of biological and ecological traits for marine species so as to prioritise the development of a world database on marine species traits. In addition, the ‘status’ of species for conservation, that is, whether they are introduced or invasive, of fishery or aquaculture interest, harmful, or used as an ecological indicator, were reviewed because these attributes are of particular interest to society. Whereas traits are an enduring characteristic of a species and/or population, a species status may vary geographically and over time. Criteria for selecting traits were that they could be applied to most taxa, were easily available, and their inclusion would result in new research and/or management applications. Numerical traits were favoured over categorical. Habitat was excluded as it can be derived from a selection of these traits. Ten traits were prioritized for inclusion in the most comprehensive open access database on marine species (World Register of Marine Species), namely taxonomic classification, environment, geography, depth, substratum, mobility, skeleton, diet, body size and reproduction. These traits and statuses are being added to the database and new use cases may further subdivide and expand upon them.

Ecological controls on biogeochemical fluxes in the western Antarctic Peninsula studied with an inverse foodweb model

Sea ice in the western Antarctic Peninsula (WAP) region is both highly variable and rapidly changing. In the Palmer Station region, the ice season duration has decreased by 92 d since 1978. The sea-ice changes affect ocean stratification and freshwater balance and in turn impact every component of the polar marine ecosystem. Long-term observations from the WAP nearshore and offshore regions show a pattern of chlorophyll (Chl) variability with three to five years of negative Chl anomalies interrupted by one or two years of positive anomalies (high and low Chl regimes). Both field observations and results from an inverse food-web model show that these high and low Chl regimes differed significantly from each other, with high primary productivity and net community production (NCP) and other rates associated with the high Chl years and low rates with low Chl years. Gross primary production rates (GPP) averaged 30 mmolC.m-2.d-1 in the low Chl years and 100 mmolC.m-2.d-1 in the high Chl years. Both large and small phytoplankton were more abundant and more productive in high Chl years than in low Chl years. Similarly, krill were more important as grazers in high Chl years, but did not differ from microzooplankton in high or low Chl years. Microzooplankton did not differ between high and low Chl years. Net community production differed significantly between high and low Chl years, but mobilized a similar proportion of GPP in both high and low Chl years. The composition of the NCP was uniform in high and low Chl years. These results mphasize the importance of microbial components in the WAP plankton system and suggest that food webs dominated by small phytoplankton can have pathways that funnel production into NCP, and likely, export.

Conceptual Ecological Modelling of Sublittoral Rock Habitats to Inform Indicator Selection

The purpose of this study is to produce a series of Conceptual Ecological Models (CEMs) that represent sublittoral rock habitats in the UK. CEMs are diagrammatic representations of the influences and processes that occur within an ecosystem. They can be used to identify critical aspects of an ecosystem that may be studied further, or serve as the basis for the selection of indicators for environmental monitoring purposes. The models produced by this project are control diagrams, representing the unimpacted state of the environment free from anthropogenic pressures. It is intended that the models produced by this project will be used to guide indicator selection for the monitoring of this habitat in UK waters. CEMs may eventually be produced for a range of habitat types defined under the UK Marine Biodiversity Monitoring R&D Programme (UKMBMP), which, along with stressor models, are designed to show the interactions within impacted habitats, would form the basis of a robust method for indicator selection. This project builds on the work to develop CEMs for shallow sublittoral coarse sediment habitats (Alexander et al 2014). The project scope included those habitats defined as ‘sublittoral rock’. This definition includes those habitats that fall into the EUNIS Level 3 classifications A3.1 Atlantic and Mediterranean high energy infralittoral rock, A3.2 Atlantic and Mediterranean moderate energy infralittoral rock, A3.3 Atlantic and Mediterranean low energy infralittoral rock, A4.1 Atlantic and Mediterranean high energy circalittoral rock, A4.2 Atlantic and Mediterranean moderate energy circalittoral rock, and A4.3 Atlantic and Mediterranean low energy circalittoral rock as well as the constituent Level 4 and 5 biotopes that are relevant to UK waters. A species list of characterising fauna to be included within the scope of the models was identified using an iterative process to refine the full list of species found within the relevant Level 5 biotopes. A literature review was conducted using a pragmatic and iterative approach to gather evidence regarding species traits and information that would be used to inform the models and characterise the interactions that occur within the sublittoral rock habitat. All information gathered during the literature review was entered into a data logging pro-forma spreadsheet that accompanies this report. Wherever possible, attempts were made to collect information from UK-specific peer-reviewed studies, although other sources were used where necessary. All data gathered was subject to a detailed confidence assessment. Expert judgement by the project team was utilised to provide information for aspects of the models for which references could not be sourced within the project timeframe. A multivariate analysis approach was adopted to assess ecologically similar groups (based on ecological and life history traits) of fauna from the identified species to form the basis of the models. A model hierarchy was developed based on these ecological groups. One general control model was produced that indicated the high-level drivers, inputs, biological assemblages, ecosystem processes and outputs that occur in sublittoral rock habitats. In addition to this, seven detailed sub-models were produced, which each focussed on a particular ecological group of fauna within the habitat: ‘macroalgae’, ‘temporarily or permanently attached active filter feeders’, ‘temporarily or permanently attached passive filter feeders’, ‘bivalves, brachiopods and other encrusting filter feeders’, ‘tube building fauna’, ‘scavengers and predatory fauna’, and ‘non-predatory mobile fauna’. Each sub-model is accompanied by an associated confidence model that presents confidence in the links between each model component. The models are split into seven levels and take spatial and temporal scale into account through their design, as well as magnitude and direction of influence. The seven levels include regional to global drivers, water column processes, local inputs/processes at the seabed, habitat and biological assemblage, output processes, local ecosystem functions, and regional to global ecosystem functions. The models indicate that whilst the high level drivers that affect each ecological group are largely similar, the output processes performed by the biota and the resulting ecosystem functions vary both in number and importance between groups. Confidence within the models as a whole is generally high, reflecting the level of information gathered during the literature review. Physical drivers which influence the ecosystem were found to be of high importance for the sublittoral rock habitat, with factors such as wave exposure, water depth and water currents noted to be crucial in defining the biological assemblages. Other important factors such as recruitment/propagule supply, and those which affect primary production, such as suspended sediments, light attenuation and water chemistry and temperature, were also noted to be key and act to influence the food sources consumed by the biological assemblages of the habitat, and the biological assemblages themselves. Output processes performed by the biological assemblages are variable between ecological groups depending on the specific flora and fauna present and the role they perform within the ecosystem. Of particular importance are the outputs performed by the macroalgae group, which are diverse in nature and exert influence over other ecological groups in the habitat. Important output processes from the habitat as a whole include primary and secondary production, bioengineering, biodeposition (in mixed sediment habitats) and the supply of propagules; these in turn influence ecosystem functions at the local scale such as nutrient and biogeochemical cycling, supply of food resources, sediment stability (in mixed sediment habitats), habitat provision and population and algae control. The export of biodiversity and organic matter, biodiversity enhancement and biotope stability are the resulting ecosystem functions that occur at the regional to global scale. Features within the models that are most useful for monitoring habitat status and change due to natural variation have been identified, as have those that may be useful for monitoring to identify anthropogenic causes of change within the ecosystem. Biological, physical and chemical features of the ecosystem have been identified as potential indicators to monitor natural variation, whereas biological factors and those physical /chemical factors most likely to affect primary production have predominantly been identified as most likely to indicate change due to anthropogenic pressures.

Assessing the sensitivity of subtidal sedimentary habitats to pressures associated with marine activities. Phase 1 Report: Rationale and proposed ecological groupings for Level 5 biotopes against which sensitivity assessments would be best undertaken.

The purpose of this study is to produce a series of Conceptual Ecological Models (CEMs) that represent sublittoral rock habitats in the UK. CEMs are diagrammatic representations of the influences and processes that occur within an ecosystem. They can be used to identify critical aspects of an ecosystem that may be studied further, or serve as the basis for the selection of indicators for environmental monitoring purposes. The models produced by this project are control diagrams, representing the unimpacted state of the environment free from anthropogenic pressures. It is intended that the models produced by this project will be used to guide indicator selection for the monitoring of this habitat in UK waters. CEMs may eventually be produced for a range of habitat types defined under the UK Marine Biodiversity Monitoring R&D Programme (UKMBMP), which, along with stressor models, are designed to show the interactions within impacted habitats, would form the basis of a robust method for indicator selection. This project builds on the work to develop CEMs for shallow sublittoral coarse sediment habitats (Alexander et al 2014). The project scope included those habitats defined as ‘sublittoral rock’. This definition includes those habitats that fall into the EUNIS Level 3 classifications A3.1 Atlantic and Mediterranean high energy infralittoral rock, A3.2 Atlantic and Mediterranean moderate energy infralittoral rock, A3.3 Atlantic and Mediterranean low energy infralittoral rock, A4.1 Atlantic and Mediterranean high energy circalittoral rock, A4.2 Atlantic and Mediterranean moderate energy circalittoral rock, and A4.3 Atlantic and Mediterranean low energy circalittoral rock as well as the constituent Level 4 and 5 biotopes that are relevant to UK waters. A species list of characterising fauna to be included within the scope of the models was identified using an iterative process to refine the full list of species found within the relevant Level 5 biotopes. A literature review was conducted using a pragmatic and iterative approach to gather evidence regarding species traits and information that would be used to inform the models and characterise the interactions that occur within the sublittoral rock habitat. All information gathered during the literature review was entered into a data logging pro-forma spreadsheet that accompanies this report. Wherever possible, attempts were made to collect information from UK-specific peer-reviewed studies, although other sources were used where necessary. All data gathered was subject to a detailed confidence assessment. Expert judgement by the project team was utilised to provide information for aspects of the models for which references could not be sourced within the project timeframe. A multivariate analysis approach was adopted to assess ecologically similar groups (based on ecological and life history traits) of fauna from the identified species to form the basis of the models. A model hierarchy was developed based on these ecological groups. One general control model was produced that indicated the high-level drivers, inputs, biological assemblages, ecosystem processes and outputs that occur in sublittoral rock habitats. In addition to this, seven detailed sub-models were produced, which each focussed on a particular ecological group of fauna within the habitat: ‘macroalgae’, ‘temporarily or permanently attached active filter feeders’, ‘temporarily or permanently attached passive filter feeders’, ‘bivalves, brachiopods and other encrusting filter feeders’, ‘tube building fauna’, ‘scavengers and predatory fauna’, and ‘non-predatory mobile fauna’. Each sub-model is accompanied by an associated confidence model that presents confidence in the links between each model component. The models are split into seven levels and take spatial and temporal scale into account through their design, as well as magnitude and direction of influence. The seven levels include regional to global drivers, water column processes, local inputs/processes at the seabed, habitat and biological assemblage, output processes, local ecosystem functions, and regional to global ecosystem functions. The models indicate that whilst the high level drivers that affect each ecological group are largely similar, the output processes performed by the biota and the resulting ecosystem functions vary both in number and importance between groups. Confidence within the models as a whole is generally high, reflecting the level of information gathered during the literature review. Physical drivers which influence the ecosystem were found to be of high importance for the sublittoral rock habitat, with factors such as wave exposure, water depth and water currents noted to be crucial in defining the biological assemblages. Other important factors such as recruitment/propagule supply, and those which affect primary production, such as suspended sediments, light attenuation and water chemistry and temperature, were also noted to be key and act to influence the food sources consumed by the biological assemblages of the habitat, and the biological assemblages themselves. Output processes performed by the biological assemblages are variable between ecological groups depending on the specific flora and fauna present and the role they perform within the ecosystem. Of particular importance are the outputs performed by the macroalgae group, which are diverse in nature and exert influence over other ecological groups in the habitat. Important output processes from the habitat as a whole include primary and secondary production, bioengineering, biodeposition (in mixed sediment habitats) and the supply of propagules; these in turn influence ecosystem functions at the local scale such as nutrient and biogeochemical cycling, supply of food resources, sediment stability (in mixed sediment habitats), habitat provision and population and algae control. The export of biodiversity and organic matter, biodiversity enhancement and biotope stability are the resulting ecosystem functions that occur at the regional to global scale. Features within the models that are most useful for monitoring habitat status and change due to natural variation have been identified, as have those that may be useful for monitoring to identify anthropogenic causes of change within the ecosystem. Biological, physical and chemical features of the ecosystem have been identified as potential indicators to monitor natural variation, whereas biological factors and those physical /chemical factors most likely to affect primary production have predominantly been identified as most likely to indicate change due to anthropogenic pressures.